Achilles de khotinsky



' thread may not become diluted by attraction UNITED STATES PATENT OFFICE.

AGHILLES DE KHOTINSKY, OF GELNHAUSEN, PRUSSIA, GERMANY.

MANUFACTURE OF CARBON FILAMENTS.

SPECIFICATION forming part of Letters Patent No. 429,535, dated June 3, 1890.

Application filed February 3, 1890. Serial No. 389,082. (No model.)

To all whom it may concern.-

Be it known that I, ACHILLES DE KnormsKY, a subject of the Emperor of Russia, residing at Gelnhausen, Kingdom-of Prussia, Germany, have invented new and useful Improvements in the Manufacture of Carbon Conductors for Electric Incandescent Lamps, whereof the following is a specification.

The subject of my invention consists in a process for rendering natural cellulose en-' tirely void of structural constitution and for producting therefrom carbon conductors for electric incandescent lamps, which are superior to those heretofore made from cellulose. For this purpose I employ threads of purified natural cellulosepreferablysuch as are made from cotton which has been freed from fatty matter and treated with muriatic or hydrofluoric acid, or both, in view of extracting all mineralsubstances. These th reads are steeped at the ordinary temperature in phosphoric acid having a specific gravity of about 1.70 and left therein about one minute. After having been taken out of the acid they are hung up in air which is as dry as possible, so that the phosphoric acid imbibed by the of moisture. The acid which is in excess drips off, while the portion remaining in the thread converts the same by acting progressively from the exterior to the interior into a translucent mass. For this conversion about twenty-four hours are required, so that its progress may conveniently be watched. The

threads in which the structural constitution Preferably awater until every trace of acid has been removed and dried. In view of making their surface smoother and their thickness more uniform they may then be passed through a draw-plate. Finally the threads are carbonized in known manner, and the conductors thus obtained are employed in incandescent lamps, as usual.

I am aware that threads of natural fibrous cellulose have heretofore been treated with sulphuric acid in view of converting them into a structureless mass of gelatinous cellulose. The sulphuric acid, however, acts so rapidly on the fibrous cellulose that it is impossible to properly control the process, many threads becoming completely distroyed, while others are only superficially acted upon; but if phosphoric acid of the prescribed degree of concentration is employed at the ordinary temperature of the air the conversion of the fibers into gelatinous cellulose goes on slowly, so that its progress maybe accurately watched. The described process, therefore, presents the advantage of aifording means for easily obtaining threads of uniform quality.

I claim as my invention The process of producing carbon conductors for electric incandescent lamps, which consists in impregnating threads of purified natural cellulose at the ordinary temperature with phosphoric acid having a specific gravity of about 1.7 O, in leaving the same to the action of the acid in dry air until their structural constitution has disappeared, in removing the phosphoric acid by treatment with a liquid adapted to separate out said acidsuch as alcohol, ether, and distilled waterand in carbonizing the amorphous thread, substantially as described.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.v

AOHILLES DE KHOTINSKY.

Witnesses:

JEAN GRUND, ALVESTO P. HOGUE. 

